<?php
/**
 * CCaptcha class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CCaptcha renders a CAPTCHA image element.
 *
 * CCaptcha is used together with {@link CCaptchaAction} to provide {@link http://en.wikipedia.org/wiki/Captcha CAPTCHA}
 * - a way of preventing site spam.
 *
 * The image element rendered by CCaptcha will display a CAPTCHA image generated
 * by an action of class {@link CCaptchaAction} belonging to the current controller.
 * By default, the action ID should be 'captcha', which can be changed by setting {@link captchaAction}.
 *
 * CCaptcha may also render a button next to the CAPTCHA image. Clicking on the button
 * will change the CAPTCHA image to be a new one in an AJAX way.
 *
 * If {@link clickableImage} is set true, clicking on the CAPTCHA image
 * will refresh the CAPTCHA.
 *
 * A {@link CCaptchaValidator} may be used to validate that the user enters
 * a verification code matching the code displayed in the CAPTCHA image.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.web.widgets.captcha
 * @since 1.0
 */
class CCaptcha extends CWidget {
    /**
     * @var string the ID of the action that should provide CAPTCHA image. Defaults to 'captcha',
     * meaning the 'captcha' action of the current controller. This property may also
     * be in the format of 'ControllerID/ActionID'. Underneath, this property is used
     * by {@link CController::createUrl} to create the URL that would serve the CAPTCHA image.
     * The action has to be of {@link CCaptchaAction}.
     */
    public $captchaAction = 'captcha';
    /**
     * @var boolean whether to display a button next to the CAPTCHA image. Clicking on the button
     * will cause the CAPTCHA image to be changed to a new one. Defaults to true.
     */
    public $showRefreshButton = true;
    /**
     * @var boolean whether to allow clicking on the CAPTCHA image to refresh the CAPTCHA letters.
     * Defaults to false. Hint: you may want to set {@link showRefreshButton} to false if you set
     * this property to be true because they serve for the same purpose.
     * To enhance accessibility, you may set {@link imageOptions} to provide hints to end-users that
     * the image is clickable.
     */
    public $clickableImage = false;
    /**
     * @var string the label for the refresh button. Defaults to 'Get a new code'.
     */
    public $buttonLabel;
    /**
     * @var string the type of the refresh button. This should be either 'link' or 'button'.
     * The former refers to hyperlink button while the latter a normal push button.
     * Defaults to 'link'.
     */
    public $buttonType = 'link';
    /**
     * @var array HTML attributes to be applied to the rendered image element.
     */
    public $imageOptions = array();
    /**
     * @var array HTML attributes to be applied to the rendered refresh button element.
     */
    public $buttonOptions = array();


    /**
     * Renders the widget.
     */
    public function run() {
        if (self::checkRequirements('imagick') || self::checkRequirements('gd')) {
            $this->renderImage();
            $this->registerClientScript();
        } else
            throw new CException(Yii::t('yii', 'GD with FreeType or ImageMagick PHP extensions are required.'));
    }

    /**
     * Renders the CAPTCHA image.
     */
    protected function renderImage() {
        if (!isset($this->imageOptions['id']))
            $this->imageOptions['id'] = $this->getId();

        $url = $this->getController()->createUrl($this->captchaAction, array('v' => uniqid()));
        $alt = isset($this->imageOptions['alt']) ? $this->imageOptions['alt'] : '';
        echo CHtml::image($url, $alt, $this->imageOptions);
    }

    /**
     * Registers the needed client scripts.
     */
    public function registerClientScript() {
        $cs = Yii::app()->clientScript;
        $id = $this->imageOptions['id'];
        $url = $this->getController()->createUrl($this->captchaAction, array(CCaptchaAction::REFRESH_GET_VAR => true));

        $js = "";
        if ($this->showRefreshButton) {
            // reserve a place in the registered script so that any enclosing button js code appears after the captcha js
            $cs->registerScript('Yii.CCaptcha#' . $id, '// dummy');
            $label = $this->buttonLabel === null ? Yii::t('yii', 'Get a new code') : $this->buttonLabel;
            $options = $this->buttonOptions;
            if (isset($options['id']))
                $buttonID = $options['id'];
            else
                $buttonID = $options['id'] = $id . '_button';
            if ($this->buttonType === 'button')
                $html = CHtml::button($label, $options);
            else
                $html = CHtml::link($label, $url, $options);
            $js = "jQuery('#$id').after(" . CJSON::encode($html) . ");";
            $selector = "#$buttonID";
        }

        if ($this->clickableImage)
            $selector = isset($selector) ? "$selector, #$id" : "#$id";

        if (!isset($selector))
            return;

        $js .= "
jQuery(document).on('click', '$selector', function(){
	jQuery.ajax({
		url: " . CJSON::encode($url) . ",
		dataType: 'json',
		cache: false,
		success: function(data) {
			jQuery('#$id').attr('src', data['url']);
			jQuery('body').data('{$this->captchaAction}.hash', [data['hash1'], data['hash2']]);
		}
	});
	return false;
});
";
        $cs->registerScript('Yii.CCaptcha#' . $id, $js);
    }

    /**
     * Checks if specified graphic extension support is loaded.
     * @param string $extension name to be checked. Possible values are 'gd', 'imagick' and null.
     * Default value is null meaning that both extensions will be checked. This parameter
     * is available since 1.1.13.
     * @return boolean true if ImageMagick extension with PNG support or GD with FreeType support is loaded,
     * otherwise false
     * @since 1.1.5
     */
    public static function checkRequirements($extension = null) {
        if (extension_loaded('imagick')) {
            $imagick = new Imagick();
            $imagickFormats = $imagick->queryFormats('PNG');
        }
        if (extension_loaded('gd')) {
            $gdInfo = gd_info();
        }
        if ($extension === null) {
            if (isset($imagickFormats) && in_array('PNG', $imagickFormats))
                return true;
            if (isset($gdInfo) && $gdInfo['FreeType Support'])
                return true;
        } elseif ($extension == 'imagick' && isset($imagickFormats) && in_array('PNG', $imagickFormats))
            return true; elseif ($extension == 'gd' && isset($gdInfo) && $gdInfo['FreeType Support'])
            return true;
        return false;
    }
}
